#### Bug, feature request, or proposal: Bug #### What is the expected behavior? It should not repaint on scroll #### What is the current behavior? It repaints on scroll  #### What are the steps to reproduce? https://stackblitz.com/edit/angular-material2-issue-vyd5mg #### What is the use-case or motivation for changing an existing behavior? Performance matters. #### Which versions of Angular, Material, OS, TypeScript, browsers are affected? Material 2.0.0-beta.12